#10 Process specific backup log files

A process will open outbuf/inbuf.pid.log and move it to the outbuf/inbuf.log upon close, allowing for multiple processes to be open at once

src/bytenuts.c

@@ -414,10 +414,14 @@ read_state()
 {
     struct stat st;
     char *buf;
-    char *cwd = getcwd(NULL, 0);
+    char *cwd;
     char *home = getenv("HOME");
     FILE *fd;
 
+    if (!home)
+        return 0;
+
+    cwd = getcwd(NULL, 0);
     chdir(home);
 
     fd = fopen(".config/bytenuts/inbuf.log", "r");

src/cheerios.c

@@ -25,7 +25,6 @@ int
 cheerios_start(bytenuts_t *bytenuts)
 {
     char *home = getenv("HOME");
-    char *cwd;
 
     memset(&cheerios, 0, sizeof(cheerios_t));
 
@@ -43,11 +42,25 @@ cheerios_start(bytenuts_t *bytenuts)
         }
     }
 
-    cwd = getcwd(NULL, 0);
-    chdir(home);
-    cheerios.backup = fopen(".config/bytenuts/outbuf.log", "w");
-    chdir(cwd);
-    free(cwd);
+    if (home) {
+        pid_t pid;
+        int name_len;
+
+        /* ensure that a process has a unique log */
+        pid = getpid();
+        name_len = snprintf(
+            NULL, 0,
+            "%s/.config/bytenuts/outbuf.%d.log",
+            home, pid
+        );
+        cheerios.backup_filename = calloc(1, name_len + 1);
+        snprintf(
+            cheerios.backup_filename, name_len + 1,
+            "%s/.config/bytenuts/outbuf.%d.log",
+            home, pid
+        );
+        cheerios.backup = fopen(cheerios.backup_filename, "w");
+    }
 
     pthread_cond_init(&cheerios.cond, NULL);
     pthread_mutex_init(&cheerios.lock, NULL);
@@ -138,7 +151,6 @@ cheerios_stop()
 {
     cheerios.running = 0;
     pthread_join(cheerios.thr, NULL);
-
     return 0;
 }
 
@@ -338,8 +350,33 @@ cheerios_thread(void *arg)
 
     if (cheerios.log)
         fclose(cheerios.log);
-    if (cheerios.backup)
+
+    if (cheerios.backup) {
+        char *out_filename;
+        int out_filename_len;
+        char *home = getenv("HOME");
+
+        /* do not chdir as other threads can still be running */
+        out_filename_len = snprintf(
+            NULL, 0,
+            "%s/.config/bytenuts/outbuf.log",
+            home
+        );
+        out_filename = calloc(1, out_filename_len + 1);
+        snprintf(
+            out_filename, out_filename_len + 1,
+            "%s/.config/bytenuts/outbuf.log",
+            home
+        );
+
+        /* move this processes log to the path that can be loaded on resumption */
         fclose(cheerios.backup);
+        rename(cheerios.backup_filename, out_filename);
+
+        free(out_filename);
+        free(cheerios.backup_filename);
+    }
+
     pthread_exit(NULL);
     return NULL;
 }

src/cheerios.h

@@ -35,8 +35,9 @@ typedef struct cheerios_struct {
     pthread_mutex_t *term_lock;
     int ser_fd;
     line_buffer_t lines;
-    FILE *log;
-    FILE *backup;
+    FILE *log; /* log file which was opened with -l */
+    char *backup_filename; /* realpath to the backup outbuf.pid.log */
+    FILE *backup; /* backup log file object */
     bytenuts_config_t *config;
     volatile int mode;
     pthread_cond_t cond;

src/ingest.c

@@ -40,19 +40,29 @@ ingest_start(bytenuts_t *bytenuts)
 
     HOME = getenv("HOME");
     if (HOME) {
-        char *cwd = getcwd(NULL, 0);
         int idx = 0;
-
-        chdir(HOME);
+        int name_len;
+        pid_t pid;
 
         while (!read_cmd_page(idx)) {
             idx++;
         }
 
-        ingest.history_fd = fopen(".config/bytenuts/inbuf.log", "w");
+        /* ensure that a process has a unique log */
+        pid = getpid();
+        name_len = snprintf(
+            NULL, 0,
+            "%s/.config/bytenuts/inbuf.%d.log",
+            HOME, pid
+        );
+        ingest.history_filename = calloc(1, name_len + 1);
+        snprintf(
+            ingest.history_filename, name_len + 1,
+            "%s/.config/bytenuts/inbuf.%d.log",
+            HOME, pid
+        );
 
-        chdir(cwd);
-        free(cwd);
+        ingest.history_fd = fopen(ingest.history_filename, "w");
     }
 
     if (ingest.cmd_pgs_n > 0) {
@@ -73,10 +83,6 @@ ingest_stop()
 {
     ingest.running = 0;
     pthread_join(ingest.thr, NULL);
-
-    if (ingest.history_fd)
-        fclose(ingest.history_fd);
-
     return 0;
 }
 
@@ -419,6 +425,32 @@ ingest_thread(void *arg)
         sched_yield();
     }
 
+    if (ingest.history_fd) {
+        char *in_filename;
+        int in_filename_len;
+        char *home = getenv("HOME");
+
+        /* do not chdir as other threads can still be running */
+        in_filename_len = snprintf(
+            NULL, 0,
+            "%s/.config/bytenuts/inbuf.log",
+            home
+        );
+        in_filename = calloc(1, in_filename_len + 1);
+        snprintf(
+            in_filename, in_filename_len + 1,
+            "%s/.config/bytenuts/inbuf.log",
+            home
+        );
+
+        /* move this processes history to the path that can be loaded on resumption */
+        fclose(ingest.history_fd);
+        rename(ingest.history_filename, in_filename);
+
+        free(in_filename);
+        free(ingest.history_filename);
+    }
+
     pthread_exit(NULL);
     return NULL;
 }

src/ingest.h

@@ -24,6 +24,7 @@ typedef struct ingest_struct {
     int inpos; /* cursor position within the inbuf itself */
     int inlen; /* length of the input buffer */
     char **history; /* array of strings representing the command history */
+    char *history_filename; /* realpath of inbuf.pid.log */
     FILE *history_fd;
     char tmp_history[4096]; /* copy of inbuf before we load in history */
     int history_len;